Topic | How to measure 230V AC?

Home Forums Mooshimeter Support How to measure 230V AC?

This topic contains 21 replies, has 8 voices, and was last updated by  AudyIltis 6 months, 3 weeks ago.

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  • #10921 Reply



    i just tried to measure 230V AC. So i connected one to “V” and one to “C” and put it in a power outlet.
    The mooshimeter shows me 98V.

    Is it something i am doing wrong? or something i don’t know about?
    When i measure DC it shows me the correct voltage.


    P.S.: I don’t get activation mail for the forum account.

  • #10922 Reply


    Hello have you changed on the smartphone in the app Voltage AC. If selected in the App DC can not display the correct value the Mooshimeter.

    Screenshot Mooshimeter App

  • #10923 Reply


    I just tried it again and yes. AC is selected.
    Voltage is between 98 and 100… But not 230V :(

    I am using the beta firmware though. Not sure if it worked with the released firmware.

  • #10924 Reply


    Here screenshot:

    Connected to 230V outlet (Germany):

  • #10925 Reply


    Sorry… choose the wrong link and can’t edit.
    This hopefully works:

    Screenshot of the app

    Connected to Power outlet 230V (Germany)

  • #10926 Reply



    There is sampling rate settings at bottom of your screen.. Set both to “auto” and it should be ok..

    125Hz is way too low for calculating actual 50Hz mains voltage.

  • #10927 Reply


    That did the job. Thx.
    Seems i am not smart enough for the Mooshimeter. Not Yet :)

  • #13865 Reply


    Thanks Ville!

    EDsteve – not your fault. A user interface is like a joke: if you need to explain it, it’s not very good. A couple of people have fallen in the exact same trap as you, I’ll be looking at ways to avoid it in the future.


  • #14109 Reply


    Hi James,
    I was one of them with the AC measurement problem.
    one hint: Page 7 in the Cheat Sheet says:
    “Note that AC calculations are inaccurate at buffer depths below 128”
    Sample rate is also important!
    Here my results of a test on this subject:
    input 230V AC 50 Hz (Mains in the Netherlands)
    AC Scale 600V Man
    Sample rate Hz|Buffer smpl|measured (rounded to 1V)

    Hz smpl measured
    8000 256 230
    8000 128 jumping between 0 and 230 V
    8000 64 0
    8000 32 0

    8000 256 230
    4000 256 230, also in AUTO mode
    2000 256 230
    1000 256 228
    500 256 219
    250 256 189
    125 256 100

    125 32 100

    2000 256 230
    2000 128 230
    2000 64 230
    2000 32 jumping between 0 and 230V

    1000 32 228


  • #14116 Reply


    Thank you for this thread. I came to the forum to find out why when trying to read 120VAC all I was getting was about 30VAC. I set both sample rate settings to auto and all is good (at least for that reading).

    Now to demo it at work again with the right settings to try to wash the egg off my face from Friday’s failed demo of pulling it out and plugging the probes into the wall…

  • #14124 Reply


    Thanks Harm and Sembazuru,

    My plan to avoid this problem in the future is to have the app serve a warning when the settings might result in inaccurate AC settings. I don’t want to remove the user’s control of all settings, but enough people have fallen for this trap there should be a warning.


  • #14140 Reply


    I’d rather not get constant warnings – but perhaps turn the background or text red to indicate an unusual situation? Or make the warning a once off affair?

  • #15115 Reply


    Thanks for this post. Fixed my issue.

  • #15204 Reply

    Gordon Hicks

    I had the same problem measuring 120 VAC. By adjusting both the sample rate sample count upward I was able to get a sensible reading. The AUTO settings are sketchy and give unstable results.

    Beta version:
    FW Build: 1477971088

  • #15205 Reply

    Gordon Hicks

    I’d like to see the auto settings provide the most accurate settings based on the input frequency or whatever factors are relevant. I agree that it is useful to be able to manually set the sampling to other values.

  • #15211 Reply


    Hi Gordon,

    The auto setting for sample rate and buffer depth should be setting it to 4000Hz and 256 samples when taking an AC reading. I’ve found these settings ideal for 50/60Hz AC signals. If you find a different strategy please let me know :)


  • #20032 Reply


    Is higher Hz and higher samples always more accurate?
    Does it shorten battery life?
    I am trying to monitor my building’s 230VAC for a whole week, logging to SD card.
    Just got my Mooshimeter, the included batteries were “62%” and firmware upgrading was repeating and failing, after replacing the batteries, I measured the included batteries were at 1.28V. (the fresh alkalines measured slightly over 1.6V), when it booted up with fresh batteries, it reported the firmware as already current.

    After initial tests, I am also disappointed that the log-to-microsdcard isn’t respecting the interval that I set. I choose the max which is 10 minutes (600s), but the csv I got showed that it was logging every 10 seconds instead.

    • #20034 Reply


      Is higher Hz and higher samples always more accurate?
      Basically yes. There has been little problems with 8 kHz sampling, where you can see random spikes at random times. It might be just fine for hours or screw your whole setup. I would stay at 4 kHz and lower, if possible.

      Does it shorten battery life?
      I would guess that it depends on how long it takes to take those samples, so lowest Hz and highest samples would use more energy than max Hz and lowest samples. Shorter logging interval drains batteries faster, but you should get several days in any case.

      After initial tests …
      Which firmware/app versions do you have? There was a bug that made 10 minute intervals unusable and generated 10.176 second intervals instead. That should have been fixed a long time ago, but as most of us at this forum use beta-app, its hard to say what you really get from app/play-stores outside beta program.

  • #20035 Reply


    On the Scan screen, I see “Build: 1477971088”, this is after one upgrade.
    I just received my Mooshimeter yesterday, and I installed the app from Play Store.
    Am I affected by the 10-minute bug?
    How do I get the beta app?

    I get that the “Hz” setting means how frequently the instantaneous DC voltage is measured so as to figure the AC characteristics.
    But what does the “samples” setting mean?
    Does it actually mean the number of bits used to record each sample? (i.e. bit-depth in the language used when talking about ADC and .wav)

    • #20036 Reply


      That firmware is quite old (I have 1522204715). Fw-updating has its problems and might took several tries, so those are not forced anymore to those of us that do not use 10 minute intervals etc.

      I get that the “Hz” setting means how frequently the instantaneous DC voltage is measured so as to figure the AC characteristics.
      But what does the “samples” setting mean?

      It just means how many of those dc-samples are taken in one go and then analyzed. For example, you need to allow mooshimeter to see a whole sine wave to calculate its rms-value, by keeping amount of samples large enough at the sample rate you have selected. You can check what mooshimeter really sees and uses as a base for calculations, if you go to graph mode -> config -> buffer mode. It then displays your sample buffer snapshots without processing.

    • #20037 Reply


      Thank you. Ok I understand that the “samples” setting isn’t bit-depth, it’s the number of last measurements to be kept in buffer for the mooshimeter to see the wave. I am in a 50Hz country, Auto Hz selects 4000Hz, and Auto samples selects 256 (which is the max). By my calculations, 256 samples will allow it to see 3+ complete cycles.

      I’ve joined the Beta for Play store, now loading Build 1522204715.

  • #20039 Reply


    Hi…I had the same problem measuring 120 VAC. By adjusting both the sample rate sample count upward I was able to get a sensible reading. The AUTO settings are sketchy and give unstable results.

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